Micro-electromechanical ink ejection mechanism with electro-magnetic actuation

ABSTRACT

A micro-electromechanical ink ejection mechanism for an inkjet printhead includes a substrate. A nozzle chamber structure is arranged on the substrate and defines a nozzle chamber and an outlet in fluid communication with the nozzle chamber. An ink ejection member is suspended within the chamber and is displaceable towards and away from the outlet to eject ink from the outlet. The ink ejection member is capable of electromagnetic actuation. An electromagnetic actuator is configured to actuate the ink ejection member so that ink is ejected from the outlet.

CROSS REFERENCED AND RELATED APPLICATIONS

This is a Continuation of U.S. application Ser. No. 11/272,417 filed onNov. 1, 2005, which is a Continuation of U.S. application Ser. No.11/026,129 filed on Jan. 3, 2005, now issued as U.S. Pat. No. 7,001,012,which is a Continuation of Ser. No. 10/303,238 filed Nov. 23, 2002, nowissued as U.S. Pat. No. 6,874,866 which is a continuation of U.S. Ser.No. 09/864,378 filed May 25, 2001, now issued as U.S. Pat. No. 6,471,336which is a Continuation in Part of 09/113,096 filed Jul. 10, 1998, nowissued as U.S. Pat. No. 6,264,307, all of which are herein incorporatedby reference.

FIELD OF THE INVENTION

This invention relates to a nozzle arrangement that incorporates areversible actuating mechanism. This invention also relates to aprinthead that includes a plurality of such nozzle arrangements.

BACKGROUND OF THE INVENTION

The Applicant has invented a printhead which is capable of generatingtext and images at a resolution as high as 1600 dpi. In order to achievethis high resolution, the applicant has utilized various aspects ofmicro electromechanical systems technology. The reason for this is thatsuch systems provide a means whereby ink can be ejected independentlyfrom a plurality of nozzle arrangements.

The nozzle arrangements are formed on a page width printhead. In orderto achieve the high resolutions, up to 84000 nozzle arrangements can beformed on the page width printhead. Each of these nozzle arrangements isin the form of a micro electromechanical device that incorporates atleast one working device which is displaceable to achieve or permit theejection of ink from each nozzle arrangement.

The Applicant has found that it is often advantageous continuously tocontrol the movement of such a working device in order that the workingdevice can remain stable during its movement through a path of travel.

SUMMARY OF THE INVENTION

According to a first aspect of the invention, there is provided a nozzlearrangement that is the product of an integrated circuit fabricationtechnique, the nozzle arrangement comprising

a substrate; and

an actuating mechanism that is mounted on the substrate and thatcomprises

-   -   a first member that is movable reciprocally along a path of        travel in order to perform work; and    -   at least two actuators that are arranged with respect to the        first member to act on the first member, the actuators being        configured so that the first member is under the influence of at        least one of the actuators at substantially all points along the        path of travel.

According to a second aspect of the invention there is provided a nozzlearrangement which is the product of an integrated circuit fabricationtechnique, the nozzle arrangement comprising

a substrate;

a first member that is mounted on the substrate and that is movablereciprocally along a path of travel in order to perform work, the firstmember being configured to be so movable under the influence of amagnetic field of suitable strength; and

at least two electromagnetic actuators that are arranged with respect tothe first member to act on the first member, the actuators being capableof generating a magnetic field and of reversing the polarity of thatfield, the actuators being connectable to a suitable control system topermit the actuators to act synchronously so that the first member isunder the influence of said at least two actuators while beingreciprocally moved along the path of travel by magnetic fields generatedby said at least two actuators.

According to a third aspect of the invention, there is provided an inkjet printhead, which is the product of an integrated circuit fabricationtechnique, the ink jet printhead comprising

a substrate; and

a plurality of nozzle arrangements that are arranged on the substrate,each nozzle arrangement comprising

-   -   nozzle chamber walls that define a nozzle chamber; and    -   an actuating mechanism that is mounted on the substrate and that        comprises

a first member that is movable reciprocally along a path of travel inorder to eject ink from the nozzle chamber and at least two actuatorsthat are arranged with respect to the first member to act on the firstmember, the actuators being configured so that the first member is underthe influence of at least one of the actuators at substantially allpoints along the path of travel.

In a fourth aspect, embodiments of the invention provide a nozzlearrangement comprising

a substrate;

an actuating mechanism that is mounted on the substrate and thatcomprises a first member that is movable reciprocally along a path oftravel between first and second positions; and

at least actuators that are arranged with respect to the first member toact on the first member, the actuators being configured so that thefirst member is under the influence of at least one of the actuators atsubstantially all points along the path of travel.

In a fifth aspect, embodiments of the invention provide a nozzlearrangement is comprising

a substrate;

a first member that is mounted on the substrate and that is movablereciprocally along a path of travel in order to perform work, the firstmember being configured to be so movable under the influence of amagnetic field of suitable strength; and

at least two electromagnetic actuators that are arranged with respect tothe first member to act on the first member, the actuators being capableof generating a magnetic field and of reversing the polarity of thatfield, the actuators being connectable to a suitable control system topermit the actuators to act synchronously so that the first member isunder the influence of said at least two actuators while beingreciprocally moved along the path of travel by magnetic fields generatedby said at least two actuators.

In a sixth aspect, embodiments of the invention provide an inkjetprinthead comprising

a substrate; and

a plurality of nozzle arrangements that are arranged on the substrate,each nozzle arrangement comprising

nozzle chamber walls that define a nozzle chamber; and

an actuating mechanism mounted on the substrate and comprises a firstmember that is movable reciprocally along a path of travel in order toeject ink from the nozzle chamber and at least two actuators that arearranged with respect to the first member to act on the first member,the actuators being configured so that the first member is under theinfluence of at least one of the actuators at substantially all pointsalong the path of travel.

The invention is now described, by way of examples, with reference tothe accompanying drawings. The specific nature of the followingdescription should not be construed as limiting the scope of the abovesummary.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings,

FIG. 1 shows a schematic, three dimensional view of a first embodimentof a nozzle arrangement, in accordance with the invention, for an inkjet printhead;

FIG. 2 shows an exploded view of the nozzle arrangement of FIG. 1;

FIG. 3 shows a schematic side view of a second embodiment of a nozzlearrangement, in accordance with the invention, for an ink jet printhead;

FIG. 4 shows a schematic, three dimensional view of a third embodimentof a nozzle arrangement, in accordance with the invention, for an inkjet printhead;

FIG. 5 shows the nozzle arrangement of FIG. 4 in an at rest condition;

FIG. 6 shows the nozzle arrangement of FIG. 4 with one of its actuatorsactivated;

FIG. 7 shows the nozzle arrangement of FIG. 4 in a neutral condition;

FIG. 8 shows the nozzle arrangement of FIG. 4 with another of itsactuators activated;

FIG. 9 shows the nozzle arrangement of FIG. 4 in a neutral condition;and

FIG. 10 shows a schematic, three dimensional view of a fourth embodimentof a nozzle arrangement, in accordance with the invention, for an inkjet printhead.

DETAILED DESCRIPTION OF THE DRAWINGS

In FIGS. 1 and 2, reference numeral 10 generally indicates a nozzlearrangement 10, in accordance with the invention, for an ink jetprinthead.

The nozzle arrangement 10 is one of a plurality of nozzle arrangementsformed on a wafer substrate 14 to define a page width printhead chip.

The wafer substrate 14 has a drive circuitry layer 16 positioned on thesubstrate 14. A passivation layer 18 is positioned on the drivecircuitry layer 16.

The nozzle arrangement 10 includes nozzle chamber walls 20 formed in adeposition and etching process to define a nozzle chamber 22. A roof 24spans the walls 20 and defines an ink ejection port 26 from which ink isejected, in use.

An actuating mechanism 12 is positioned within the nozzle chamber 22.

The actuating mechanism 12 includes a pair of opposed actuators 28 thatare mounted through the passivation layer 18 to be in electricalconnection with the drive circuitry layer 16.

The actuators 28 are positioned on each side of an inlet 30 of thenozzle chamber 22. The inlet 30 is defined by a number of inlet openings32 formed in the layers 16, 18 to be in fluid communication with aninlet channel 34 defined through the wafer substrate 14.

The actuating mechanism 12 includes a working device in the form of ashutter member 36 that is mounted between and to the actuators 28 tospan the inlet 30. The shutter member 36 has a number of openings 38defined therein. The shutter member openings 38 correspond with theinlet openings 32 with the shutter member 36 being displaceable betweena closed position in which the sets of openings 32, 38 are out ofregister so that the inlet 30 is closed and an open position in whichthe openings 32, 38 are in register, thereby opening the inlet 30. Theshutter member 36 is shown in its closed position in FIG. 1.

The actuators 28 are connected to the drive circuitry layer 16 which, inturn, is connected to a control system so that the actuators 28 can beactivated in a substantially synchronous manner.

Each actuator 28 includes a heater element 40 connected, at ends 42 ofthe heater element 40, to the circuitry layer 16 at vias 44. The heaterelements 40 are positioned within respective actuator arms 46. Eachactuator arm 46 is of a material with a coefficient of thermal expansionthat is suitably high so that, on heating, the subsequent expansion ofthe material is sufficient to perform work, in this case, the moving ofthe shutter member 36 between the open and closed positions. Ends 48 ofeach actuator arm 46 are fast with the layers 16, 18 while anintermediate portion 50 of each actuator arm 46 is free to move withrespect to the layers 16, 18. Thus, it will be appreciated that, onexpansion of the actuator arms 46, the actuator arms 46 are constrainedto bend in a particular direction. In this particular example, theactuator arms 46 are pre-formed so that they each bend towards the samedirection. It follows that, by ensuring that substantially identicalsignals are provided to the heater element 40, both actuator arms 46will bend, in a synchronous manner, in the same direction, effectivelypushing and pulling the shutter member 36 between the open and closedpositions.

The actuator arms 46 and the shutter member 36 can be configured sothat, prior to bending, the shutter member 36 is in its closed position.

For this purpose, the actuator arms 46 may be of a material having asuitable Young's modulus to ensure that the actuator arms act on theshutter member 36 to move the shutter member 36 back into a closedposition upon cooling of the actuator arms 46.

In FIG. 3, reference numeral 60 generally indicates a second embodimentof a nozzle arrangement in accordance with the invention, whichincorporates an actuating mechanism 62. With reference to FIGS. 1 and 2,like reference numerals refer to like parts, unless otherwise specified.

The actuating mechanism 62 includes a moving device in the form of apaddle 64 which is mounted in a displaceable manner between the nozzlechamber walls 20 to span the nozzle chamber 22. In particular, thepaddle 24 is displaceable between a lowered position as indicated by thearrow 66 and a raised position as indicated by the arrow 68. The paddle64 is configured so that, as the paddle moves from the lowered positionto the raised position, ink can be ejected from the nozzle chamber 22out of the ink ejection port 26.

The actuating mechanism 62 includes a pair of spaced toroidal magneticfield generators 70, in particular, a lower magnetic field generator70.1 and an upper magnetic field generator 70.2. Each of the magneticfield generators 70 has a wound coil 72 which is connected to the drivecircuitry layer 16. It follows, therefore, that it is to be appreciatedthat by having the drive circuitry layer 16 configured in a suitablemanner, it is possible to create a magnetic field with either of thegenerators 70 of a desired polarity and even to reverse the polaritieswhen required. This can be done simply by controlling the direction ofthe current through the coils 72 as indicated by the directional symbols73.

The paddle 64 is divided into an upper portion having one of a negativeand a positive polarity and a lower portion having the other of thenegative and positive polarities. In particular, the paddle 64 is apermanent magnet. It follows, therefore, that with suitably strongfields being generated by the generators 70, the paddle 64 can be drivenboth towards and away from the ink ejection port 26 depending on theoperation of the drive circuitry layer 16.

In FIGS. 4 to 9, reference numeral 80 generally indicates a thirdembodiment of a nozzle arrangement, in accordance with the invention.With reference to FIGS. 1 to 3, like reference numerals refer to likeparts, unless otherwise specified.

The roof 24 of the nozzle arrangement 80 has two ink ejection ports 82and 84 defined therein. The nozzle chamber 22 is divided into a firstpart 22.1 and a second part 22.2, by a partitioning wall 87 that dependsfrom the roof 24. An ink ejection member in the form of a paddle 86 ispivotally mounted on one of the walls 20 to extend into the first part22.1 of the nozzle chamber 22. The paddle 86 is pivotal towards and awayfrom the ink ejection port 82. The nozzle chamber 22 and the paddle 86are configured so that, as the paddle 86 is pivoted towards the inkejection port 82, ink is ejected from the ink ejection port 82 and asthe paddle 86 is pivoted away from the ink ejection port 82, ink isejected from the ink ejection port 84.

A distal end of an effort arm 88 is connected to the paddle 86 outsideof said one of the walls 20. Thus, said one of the walls 20 acts as afulcrum with the paddle 86 defining a load arm. A proximal end of theeffort arm 88 is connected to a distal end of an actuator arm 90.

The actuator arm 90 is of a resiliently flexible material such aspolytetrafluoroethylene (PTFE). A proximal end of the actuator arm 90 isconnected to a support post 92 which extends from the drive circuitrylayer 16. The actuator arm 90 has two pairs of opposed sides 94 and 102.

A thermal actuator in the form of a heater element 96 is fixed to eachof the pair of opposed sides 94 of the actuator arm 90, with one of theheater elements 96 being positioned between the substrate 14 and theactuator arm 90. Each heater element 96 is of a conductive materialwhich expands readily as a result of resistive heating.

Each heater element 96 is electrically connected to the drive circuitrylayer 16 via the support post 92. Thus, the actuator arm 90 can be madeto bend towards or away from the substrate 14, depending on which of theheater elements 96 is activated by the drive circuitry within the layer.It follows that the paddle 86 can be driven towards or away from the inkejection port 82, depending on which of the heater elements 96 areactivated. This can readily be seen in FIGS. 5 to 9. For example FIG. 6shows a result of the heater element 96 upon the actuator arm 90 beingheated, while FIG. 8 shows a result of the heater element 96 beneath thearm 90 being heated.

In FIG. 10, reference numeral 100 generally indicates a fourthembodiment of a nozzle arrangement, in accordance with the invention.With reference to FIGS. 1 to 9, like reference numerals refer to likeparts, unless otherwise specified.

The nozzle arrangement 100 is substantially the same as the nozzlearrangement 80, for the purposes of this invention. The primarydifference is that the heater elements 96 are positioned on each of thepair of opposed sides 102 so that movement of the actuator arm is in aplane substantially parallel to the substrate 14, rather than in a planesubstantially normal to the substrate 14 as is the case with the nozzlearrangement 80.

Applicant believes that this invention provides a means whereby movementof an actuator in a nozzle arrangement that is the product of anintegrated circuit fabrication technique can be controlled in a stablemanner. This ensures consistency of operation, which is extremelyimportant in such nozzle arrangements.

1. A micro-electromechanical ink ejection mechanism for an inkjetprinthead, the ink ejection mechanism comprising: a substrate; a nozzlechamber structure arranged on the substrate and defining a nozzlechamber and an outlet in fluid communication with the nozzle chamber; aink ejection member suspended within the chamber and displaceabletowards and away from the outlet to eject ink from the outlet, the inkejection member being capable of electromagnetic actuation; and anelectromagnetic actuator configured to actuate the ink ejection memberso that ink is ejected from the outlet.
 2. A micro-electromechanical inkejection mechanism as claimed in claim 1, wherein the ink ejectionmember is magnetic.
 3. A micro-electromechanical ink ejection mechanismas claimed in claim 2, further comprising a resilient fastening meanswhich fastens the permanent magnet to the nozzle chamber structure andthereby suspends the permanent magnet within the chamber.
 4. Amicro-electromechanical ink ejection mechanism as claimed in claim 2,wherein the ink ejection member comprises a pair of adjoining portions,one of the portions being positively polarized and the other beingnegatively polarized.
 5. A micro-electromechanical ink ejectionmechanism as claimed in claim 4, wherein the ink ejection member is inthe form of a paddle with one of said adjoining portions defining onelayer of the paddle and the other of said adjoining portions defininganother layer of the paddle.
 6. A micro-electromechanical ink ejectionmechanism as claimed in claim 1, wherein the substrate comprises a wafersubstrate layer, and a drive circuitry layer deposited on the wafersubstrate layer and configured to drive the actuator.
 7. Amicro-electromechanical ink ejection mechanism as claimed in claim 1,wherein the actuator comprises a pair of coils each located within thechamber on a respective side of the ink ejection member.